You’re missing the point Tam. They haven’t asked him to window clean for a week. They think he’s some sort of odd job man that will drop his work at their say so & go sweep a carpark etc for a week. It’s a p take in my opinion.
What im taking from it is the person has been advertising to gain some work, which would mean to me that the person hasn’t got enough work at the moment and needs space filled, so someone who needs cover has asked him if he would consider doing it. If I didn’t have enough customers and an opportunity presented itself where I could make some extra cash between doing my work then id take it, £13 an hour is better than £0 an hour sitting in the house. If the op hasn’t got enough work then take the guys offer, better in your pocket than someone else’s, if you dont need the money and would rather not then fair enough, who knows though, this work could then lead into more work for your windows depending if theres shops there etc and you get talking to them.